Protesters gathered at 30th Street Station Wednesday afternoon to rally against a grand jury's decision not to indict Ferguson police officer Darren Wilson in the shooting death of unarmed teenager Michael Brown.

Between 4 and 4:15 p.m., participants staged a "die-in," dropping to the floor of the station's main concourse.

They planned to remain there for four minutes and 30 seconds to recognize the four hours and 30 minutes Brown's body was left on the ground, according to a Facebook event listing.

Around 4:20 p.m., the protesters embarked from the station on a march toward Center City, initially slated to end at City Hall.

Chanting and armed with banners and signs, some participants tried to disrupt the flow of traffic in an attempt to ensure their voices were heard. They were met with a robust police presence.

Protesters also decried a grand jury's decision not to bring charges against a New York City police officer in connection with the death of Eric Garner, who was placed in a chokehold during a stop on Staten Island.

Participants apparently departed from previously announced plans to march from the station directly to City Hall. As of 5 p.m., it wasn't clear exactly where the rally was headed.

By 5:30 p.m., protesters appeared to have resumed their originally scheduled route. After winding through several streets in the Art Museum Area, they began to make their way toward City Hall.

In the City Hall courtyard, they ran into opening festivities for Philadelphia's holiday tree-lighting ceremony, which was scheduled to officially begin at 7 p.m. Mayor Michael Nutter was scheduled to light the tree shortly before 8 p.m.

After several hours of dueling protest chants and Christmas carols, the proceedings went forward as planned - more or less.